Internal combustion engine for aircraft



Feb. 16, 1943. c. H. WlEGMA-N INTERNAL COMBUSTION ENGINE FOR AIRCRAFTFiled June 10, 1959 4 Sheets-Sheet 1 Feb.'16, 1943. c. H. WIEGMANINTERNAL COMBUSTION ENGINE FOR AIRCRAFT 4 Sheets-Sheet 2 Filed June 10,1939 fi 9 A J i1} w 1 1| 7 p G j a w 9 o 3 w w J a@ 5 a; a. I /7 6 "m2 MM5 5 Feb. 16, 1943. v c, wlEGMAN 2,311,146

' INTERNAL COMBUSTION ENGINE FOR AIRCRAFT Filed June 10, 1959 4 Sheets-Shet 3 v razzaeffl l'sgmalz/ fl ir Feb. 16, 1943. c. H. WIEGMAN2,311,146

INTERNAL COMBUSTION ENGINE FOR AIRCRAFT '4 Sheets-Sheet 4 Filed June 10,1939 (Zane Patented Feb. 16, 1943' UNlTED S ATES PA T oFFIcs AClarence]!- willi'amsmlhaalgnor,

bymesne ta,toTheAvhtion assignmen ration, New York, N. Y, a corporationof Deta- Application June 10,1939, Serial at. 210,415

8 Claims. (Cl. 123-56) The present invention relates generally tointernal combustion engines. More particularlytheinvention relates tothat type 'of internal combustion engine which is d primarily formounting in the front portion of the fuselage of an airplane, and hasthe cylinders thereof dis.-'

cylinder type in which the various parts thereof are arranged in a novelmanner and are so designed and constructed that they maybe readilydismantled in connection with maintenance, inspection or repair;

A further object of the invention is to provide an internal combustionengine of the type and character under consideration which includessimple and extremely ,emcient lubricating means for the rocker arms inthe rocker boxes and is designed to provide maximum visibility for thepilot or operator of the airplane in which the engine is installed.

A still further object of the invention is to prodetail the constructionand deal!! of ders, the cylinder heads and the mechanism for operatingthe valves;

Figure 5 is a vertical longitudinal sectiontakenonthelinei-Joffigureiiandshowing the arrangement and design of thecrank shaft and cam shaft of'the engine; v

Figure 6 is a vertical transverse section taken on the line H of Figure5 and illustrating in detail the gearing whereby the cam shaft isdrivenfromthecrankshaftoftheengine;

Figure-l is an inner face view of the casing at the rear end of theengine crank case for enclosing the cam shaft gearing;

Figure 8 is a perspective of the two castings which serve to form thecrankcase and cylinders of the engine; t

Figure 9 is a perspective of the sump casting atthebcttomofthecrankcase;4

Figure 10 is a perspective of one of the cylinder heads; 4

Figure 11 is an enlarged end view showing one or the rocker boxes at theouter ends of the cylinder heads without its cover and illustrating indetail the arrangement and design of the valve actuating rocker arms;

vide an internal combustion engine of the hori- I rental opposedcylinder type which is extremely light in weight and occupies but asmall amount of space.

Other obiects of the invention and the various advantages and c of thepresent internal combustion engine will be apparent from :1consideration of the following detailed descrip- The invention consistsin the several novel fea-- tures which are hereinafter set forth and aremore particularly defined by claims at the conclusion hereof.

In the drawings which accompany and form a part of this specification ordisclosure and in which like numerals of reference denote correspondingparts throughout the several views:

Figure 1 is a plan of an internal combustion engine embodying theinvention:

Figure 1" is a vertical longitudinal section on the line l -l of Figure1; v

Figure 2 is a front view ofthe engine;

Figure 3 is a fragmentary horizontal section;

Figure 4 is a vertical section taken transverseontheline'Hotr'iguresandillustiatingin Figure 12 is an inner face viewof one of the covers forthe rocker boxes;.-Flgure13isanenlargedsectioncfone ofthe tappets for actuating the pushrods of the engine; and

Figure 14 is a vertical section on the line Il-il of l'lgilre 13.

The internal combustion engine which is shown in the drawingsconstitutes the preferred embodiment of the invention. It is designedprimarily to fonnthe propulsion medium for an airplane and comprises asthe'main or essential parts thereof a pair of complemental crank caseand cylinder forming castings ii, a set of cyllnderheads ",a crank shaftil, a set of pistonsil, a. cam shaft It, and a sump casting 2|.

The castings I! are complemental and, as

' shown in the drawings, are positioned in o p s relation. The innerparts of the castings l5 deflnetheenglnecrankcaseandareshapedto form apair of opposed horizontally dongated substantiallyeparallel outer sidewalls II, a pair of horizontally aligned abutting front walls 22, a pairof horizontally aligned intermediate walls 23, and a pair ofhorizontally aligned abutting rearwalls 2|. {through-bolts ii are fixedin the inner faces of the side, intermediate and rear walls of one ofthe castings and these bolts extend through aligned holes in the front,interthe cylinto form a pair of opposed semi-cylindrical're-- cesses 2'!and these are longitudinally aligned with the recesses 26 in the frontwalls 22 and together define an opening for an inboard central bearingfor the crank shaft. The upper inner.

portions of the rear wells 24 of the inner parts of the castings I5 areshaped to form a pair of complemental opposed semi-cylindrical recesses28 and these are longitudinally aligned with the recesses 26 and 21 andform a bearing opening for the rear end of the crank shaft ll. .The camshaft 19 of the engine is disposed beneath and in parallel relation withthe crank shaft and is driven by the latter, as hereinafter described.The inner lower portions of the front walls 22 are shaped to form a pairof opposed complemental semi-cylindrical recesses 29 and theseconstitute or form a bearing opening for the front end of the cam shaft.The inner lower portions of the intermediate walls 23 are shaped to forma pair of opposed complemental semi-cylindrical recesses 30 and theseare aligned with the recesses 29 and form an opening for a centralinboard bearing for the cam shaft. The inner lower portions of the rearwalls 24'of the inner parts of the castings it are shaped to form a pairof opposed complemental semi-cylindrical recesses 3| and these arelongitudinally aligned with the recesses 28 and 30 and together form acylindrical bearing opening for the rear end of the cam shaft. Inaddition to the front, intermediate and rear walls 22, 28 and, the innercrank case forming parts of the castings I5 embody or ineludehorizontally extending webs 32. These webs extend between the lowerportions of the front, intermediate and rear walls and are joined to thelower portions of the side walls 2|. They.

serve to cross-connect the various walls constituting the inner crankcase forming parts of the two castings l5 and operate to strengthen andlend rigidity to the castings I! as a whole. The inner ends of the webs32 of one casting are preferably spaced from the inner ends of the websof the other casting. At the lower corners of the side walls-2| fourlaterally extending lugs 23 v are provided. These embody verticallyextending bolt holes therethrough and are adapted for use in mountingthe engine in place. The bottom of the crank case whichis defined by theside, front, intermediate and end walls is closed or sealed by means ofthe sump casting 2|. The latter is disposed beneath the inner parts ofthe complemental castings l5 and forms a, reser-- voir or'tank for acolumn of .oil or other lubricant for the operating parts of the engine.The upper' margin of the casting embodies an integral horizontallyextending flange l4 and this flange fits, against and is secured byvertical bolts to a correspondingly shaped bottom flange 35. The latteris formed integrally with and as ly'shaped flange 21 on the inner partsof the castings i5 andisremovablysecuredtosaid flange II by verticalbolts 38. 36 and the sump casting 24 assist the throughbolts in securingtogether and holding against separation the castings ll. When it isdesired to separate the castings in connection with maintenance, repairor inspectionof the operating parts of the engine, it is only necessaryto remove the cover plate 24 and the sump casting 22 and then releasethe through-bolts 2! by re- Inspection of or access to the crank shaftII and moving the'nuts on the threaded ends thereof.

the cam shaft II is obtained by removing the bolts 38 and raising thecover plate 2'.

- The outer parts of the two complemental castings II are formedintegrally with the inner parts and are shaped to form four horizontallyextending cylinders 39' as shown in Figures 1 and 8. There are twocylinders at each side of the engine, the cylinders at one side of theengine being arranged in opposed relation with those at the other side.The cylinders 20 are longitudinally bored from one end thereofto theother and communicate with the interior of the crank case byway ofcircular openings in thevside walls 2|. They slidably support pistons l8and are separated by spaces 40. Annular fins 4| surround and are formedintegrally with the cylinders 39. These fins are spaced apart laterallyand constitute heat exchange or transfer means for use in air cooling ofthe cylinders. They sur-' round the central and outer end portions ofthe cylinders and are of substantially uniform diami eter. The adjacentportions of the fins on the central inner portions of'the cylinders areformed integrally with one another, as shown in Figures 1 and 3, and asa-result the castings I! are materially strengthened without anysubstantial increase in weight. The fins 4! around the outer ends of thecylinders are not cross-connected or attached and hence such outer endsof the cylinders are free or independent of one another and permitted toexpand or contract each independently of the others. i

The cylinder heads l4 correspond in number to, and are associatedrespectively with the outer ends of, the cylinders 29. They are in theform of metal castings and consist of upper inner end parts 42, lowerouter end parts 44, and intermediate parts 44 between the upper endportions of the outer end parts and the lower portions 'of the inner endparts. The inner end parts 42 are bolted or otherwise removably securedin sealed relation against the outer ends of the cylinders 30 and areoutwardly bulged or dome-shaped. They define combustion chambers 45 atthe out er ends of the cylinders and have annular laterally spacedintegrally formed fins 4! for cooling purposes. The central portions ofthe upper inner end parts 42 of the cylinder heads have outwardly andupwardly inclined internally threaded holes 41. These hole'scommunicatewith the combustion chambers 45 and serve as seats for the inner ends ofa set of spark plugs 44. By reason of the location and angularity of theholes -4'l the spark plugs 44 are located for the most part outwards ofthe cylinders and hence do' not interfere with the vision of the pilotor operator The cover plate controlledbymeansofmushroomtypeexhaustvalvesll. Th'epsrtsliofthecylinderheedslihavecoolingiinsliandarecored-.areprovidedwithinletsleevesli.

Theexhaustesilarepositimedins'idebysiderelationwiththeinletpassagesllandcommunicatewithandleaddownwlrdlyfrom' theexhaust ports I.Thelowerendsofthe exhaust es I! are provided with exhaustsleeves Il. Asshowninl'igure 3the inletesilinth'ecylinderheadsforthe fore or frontcylinders are located in the rear portions of the intermediate parts 4|and the inlet es in the cylinder heads for the aft or rear cylinders arelocated in the front portions of the intermediate parts of the cylinderheads. AsshowninI'igureZLtheexhaustpassages "in the cylinder heads forthe fore cylinders are catedinthefrontportionsoitheintermediate partsand the exhaust passages II in the'cylinder heads for the aft or rearcylinders are locatedintherearportionsoftheintermediate parts of thecylinder heads. The lower outer end parts 43 of the cylinder heads arepositioned outwardly of, and project below the sleeves IO and- They areformed'integrally wlththe intermediateparts N and define rocker boxesU0. The latter have open outer ends and these are normally closed bymeans of covers ll. The

covers are removably secured in place by bolts ll and when removedprovide access to the interior of the rockerboxes II; The valves ii forcontrolling the intake ports have outwardly extending stems which extendthrough and slide within sleeves 6| which project into the upper ends ofthe rocker boxes it, as shown in Figure 4.

' Compression springs 02 extend arotmd the outer projecting-ends of thestems of the valves II and serve to urge .the valves into seatedrelation with the inlet ports Is. Said springs I extend between and abutagainst washers it at the outer ends of the stems of the valves Iiandshoulders around the outer ends of the, sleeves ii. The

valves 52 for controlling the exhaust ports Ilare located inside by siderelation with the valves II and embody rearwardly and downwardlyextending stems which fit slidably in sleeves l in the upper portions ofthe intermediate parts 44 of the cylinder heads l6 and project into theupper ends of the rocker boxes 5.. Compression springs 51* extend aroundthe outer projecting ends of the stems of the valves 5! and serve tourge such valves into closed or seated relation with the exhaust portsII.

The valves BI and ll for controlling the inlet and exhaust ports 4! andIll respectively are uncylindrical recesses 29 in the inner lowerportions of the front walls 22 of the inner parts of the castings ii.The intermediate inboard bearing 12 Thelowerendsofthe-mletpakflt'swithintheopeningwhichisdeilnedb'ythe semi-cylindrical recesses andthe rearbearingllilts andissecln'ed-withintheopeningwhichisdeiinedbythesemi-cylmdricalrecesses 5 II. The tappets II, thepush-rods i1, and the rockerarmsilservetoaetuateorunseattheintake valves40. The tappets II are slidably mounted in horizontally extending,transversely disposedtuhulartsll,andareposil9 tively moved or slidoutwards during rotation of I thecamshaft libylobe's'lionsaidshaft. Thecuts ll are formed integrally with, and constitute parts of, thehorizontally extending l5 intheformofenlargedheadsand these, asshown inFigure 13 bear against the lobes 15. The

push-rods i! are disposed in and extend loosely through shroud tubes llwhich extend horizontally between thecrank case and the lower innerportions of the lower outer end parts 43 of the cylinder heads I and arepositioned beneath'the cylinders 30. The inner ends of the tubes II fltwithin holes in the lower portions of the side walls II of the innerparts of the castings II and communicate with the outer ends of thetubular enlargements ll. The outer ends of the tubes 18 are seated inholes in the lower portions of the outer lower end parts 43 of thecylinder heads and are in commlmication with 0 the lower portions of therocker boxes 58. The push-rods 81 are longer than the shroud tubes I!and have the inner ends thereof arranged in abutment with the outer endsof the tappets 65.

' The outer ends of the push-rods 61 project into cup-shapedenlargements at their outer extremities. The rocker arms 89 extendsubstantially vertically and are disposed in the rocker boxes II. Thecentral portions of the rocker arms 69 40 are Journaled on horizontallyextending stub shafts I8 and these shafts, as shown in Figure 11, aremounted in bearings II in the side portions of the outer lower-parts llof the cylinder heads II. The upper ends of the rocker arms bear againstthe outer ends of the stems of the intake valve II and the lower ends ofthe arms embody adjusting screws which bear against the cup-shapedenlargements at the outer ends of the push rods 81. when the lobes 15 onthe cam shaft strike against the inner ends of the tappets BI they forcethe tappets together with I the push-rods 81 outwards in the directionof the rocker boxes 58. Such movement on the part of the tappetsand-push-rods operates so to swing the rocker arms 89 as to unseat theintake valves 5]. The tappets 66, the push-rods 68, and the rocker arms10 are located or disposed in side by side relation with the tappets 65,the push-rods 61 and the rocker arms 69 and operate In response torotation of the cam shaft l9 to unseat the exhaust valves 52. Thetappets 6B are slidably mounted in vhorizontally extending transverselydisposed enlargements 8i and have at the inner end thereof enlargedhardened heads which abut against'lobes 82 on the cam shaft IS. Theenlargements M are positioned in parallel relation with the enlargements14 and are formed integrally with and as parts of the webs 32. The

push-rods 88 are positioned in parallel relation 70 with the push-rods$1 and extend through and fit loosely within shroud tubes 83'. Thelatter underlie the cylinders .39 and extend between the lower portionsof the side walls 22 and the inner lower portions of the outer lower endparts 43 webs". Theinner'endsofthetappetsiiare of the cylinder heads ii.The inner ends of the 1 tappets and the outer ends of said push-rodsproject intothe rocker boxes, as shown in Figure 2. The rocker arms I0extend substantially vertically and are disposed in the rocker boxes.The central portions of the rocker arms I0 are mounted on the stubshafts l0 and the lower ends of said rocker arms abut against the outerends of the push-rods 00. The upper ends of the rocker arms abut againstthe outer endsof the stems of the exhaust val es I2 and operate tounseat such valves when the tappets 00 and the pushrods 00 are shiftedoutwards in response to the action of the lobes 02 during drive orrotation of the cam shaft I0. p

' The crank shaft I1 is connected to drive the cam shaft I0 by way of apair of gears 04 and u andis .ournaled in a front bearing as.

intermediate inboard bearing 01, and arear hearing 00. The front bearing00 fits within the 3 opening which isdefined by the semi-cylindricalrecesses in the upper inner portions of the front walls 22 of the innerparts of the castings l0 and the intermediate inboard bearing 01 ntswithin the opening which is defined by the semicylindrical recesses 21.The rear bearing 00 overlies the rear bearing II for the cam shaft I0and fits within the opening which is defined by the semi-cylindricalrecesses 20 in the rear walls 24., The central portion of the crankshaft embodies crank arms- 00 and these arms, as shown in Figure 3, areconnected by connecting rods 00 to transversely extending wrist pins 0I'in the inner ends of the pistons I0. Successive explosions in thecombustion chambers 40 at the outer ends of the cylinders operate aswell understood in the art to move inwards the pistons andeffectrotation of the crank shaft. The front end of the crank shaft projectsbeyond the front bearing 00 and carries a hub 02 for a propeller (notshown). The gear 84 is mounted on the rear end of the crank shaft and,as shown in Figure 5, is disposed outwards or rearwardly of the rearwalls 24 of the inner parts of the castings I5 and is in mesh with thegear 65. The latter is suitably mounted on, and fixed to, the rear endof the cam shaft I0 and is also disposed rearwards or outwardly of therear walls 24. when the crank shaft is rotated as the result ofreciprocation of the pistons, the gears 04 and 00 operate to rotate ordrive the cam shaft I0. A plate-like casing 03 serves to cover the gears04 and 00. This casing is bolted to the rear walls and serveswith thethroughbolts 25, the cover plate 00, and the sump casting 20, releasablyor removably to secure the castings It in opposed connected relation.

A magneto 04 for supplying current to the spark plugs 40 is mounted onthe upper rear portion of the casing 03' by means of bolts or otherconnecting devices, and is arranged so that the armature shaft thereofis coaxially positioned with respect to the crank shaft II. The frontend of the magneto armature shaft is provided with a tapered spindle"and this is keyed to the hub of the cam shaftdriving gear 04.

The engine is lubricated by means of an oil pump 00. This pump comprisesa casing 01 and a pair of meshing gears -00 and 00 in the casing. Thecasing, as shown in Figure- 7., s

7 formed as an integral part of the platee casing 00 and is locatedatthe lower portion of the latter. The gears 00 and 00 arerotatablymountedinthecasing 07. The gearjliskeyed to the rear extremity of thecam shaft Iland 5 operates during drive of such shaft to rotate the gear00 and create suction in one side of the casing 01 and pressure in theother side of the casing. The suction side of the pump 00 is connectedto receive oil from the bottom of the 0 sump casting 2.0 by way of acored passage III. This passage is formed in the rear end wall of thesump casting and extends substantially vertically, as shown'in Figure 5.The outlet or pressure side of the pump 00 communicates with 5 alongitudinal passage III in the cam shaft I0 by way of a duct I02. whenthe pump is driven as the result of rotation of the cam shaft oil isdrawn into the suction side of the pump casing 01 from the bottom of thesump casting 20 20 through or via the cored passage I00. After beingplaced under pressure the oil flows through the duct I02 intothe'longitudinal passage III in the cam shaft. The cam shaft bearingsII, I2 and I0 receive oil from the passage IN by means of cross-ports inthe cam shaft. The

bearings 00, "and 00 for the crank shaft receive oil for lubricatingpurposes by way of upwardly extending oil passages I00 in the front,intermediate and rear walls of the complemental crank case and cylinderfonming'castings I5. These passages, as lead upwardly from the openingsfor the cam shaft bearings and receive oil from such bearings. In orderto lubricate the tappets. pushrods and rocker arms constituting thevalve actuating mechanism of the engine, the outer ends of the tubularenlargements I4 areprovided with upwardly facing holes I04 and the outerends of the tubular enlargements 0| are 40 provided with downwardlyfacing holes I00, as

shown in Figure 14, when the engine is in operation oil in the crankcase is splashed into the holes I04 and flows through the shroud tubesI0 into the lower portions of the rocker boxes 00. After lubricating thebearing forming portions of the rocker arms, the oil returns to the sumpcasting 20 by way of the shroud tubes 03 for the push-rods 00 and thedownwardly facing largements 0 I.

formed by abutting webs which are formed integrally with the lowerportions of the rocker box cover 00 and the lower outer end parts 40 ofthe cylinder heads I0. As shown in Figures 4 and 11, the dams I00 extendupwardly from the bottom of the rocker boxes and terminate at theirupper ends adjacent to the rocker arm supporting shafts I0. As a resultof the provision of the dams I00 the lubricant which is introduced intothe rocker boxes flows around the lower ends of the rocker arms 60 andthen over the dams and around the lower ends of the rocker arms I0 .andthence back to the sump casting 20 via the shroud tubes 00 and the holesI00. The upper endsof the rocker-arms are lubricated by oil vapor. Therocker boxes are air tight except for the passages aiforded by theshroud tubes. The shroud tubes 00 and the downwardly facing holes I05constitute vents for the rocker boxes whereby pressure and ex- ;cess oilin the rocker boxes are vented into the sump casting 20. As the resultof elimination of 7;; pressure in the rocker boxes by theaforemenshownin Figure M mm m I M the 3 2 we? p mani em m. I a

of the sim ie sunc'zl, es

m; an emerged ii [in the'uppet'pi Conduit, I, and hoflrbntai i meeainethe header 1.9m messhm ii zm'mr csen ne m W 8 the 8168M c a k eamecmmisie [wally are P d with sl v m-sm We a a s 9;

P u lliunderlie w M -P m frbmihe sump Mi 25 io ed fi af nvswi h; v aends of the'fllbes are em e-b fl ibl flfltively rs ia d I' mwm j m tubesfi i t m 1 the f"? wi -v s r nku-ca ei ..da-. lioriz n ai,t muzhof thpipes Ill x e d-upw l k nk -bolts m 3 5 T l m wa s nd orizont throushets couplings em sle s. P Th tubes z udi -t r sh .iheeeermeus-mmmovabiy111 the m 1 8 8nd fl P P a securinss e t o tosethei; assepar te y allthe same i l mmas of this. rermedis p roz .lubrie nmdisposed beneathandme w ,m ltm i m 99 case" and ;having;-atop..;flange in'iabutmentiwith m!WY? 'qhe distme a the bottom marginal 901110118105 theidnnerziparts' thewhich travels tot e r combiwtim o! the two' castinmiwandgnonnectedmemovably em t n h ehe i efifix o t 'ji si ey thereto by vertical.holtm'is .:=sepai'-ate]y;;-formed. t u Y Q Q im w 4 cover plateforclosing theropenztopvomhezcrank mm disposed F- #QPfiWB 3" #38 93 4case provided with'a marginalflangeein 'abutment M1 w im $91 3 9 i 9 .1e with-theupper marginal JDOIHOHSQOQ said inner Ming Prim? P 5 8 6 i t i909M 93 parts 10f the castings-ivandiconnectedcremovably cmmbersm de h qI thereto ,byimeans"o!yerticalgbolts,.ascrankflshait 'rnepreuuets ofe'embu t bnemanatiiis twin extendinithrough'ithefimg iea'se mip r ll lthe exhaust sleeves while fliejexhaus hiv lation;withthesidei-walisurand havingaitsefmnt are ope are dischar ed o dlmeans -endsjourna1ed2 ?in" .aa: eflfpni'sixbearingjbetween; the

or short substantially stxa isht exhaust 9 18 5 "F front-svaiis anditspreai's end dournalediima rear 'nese pipesai'esuita bly pQnnectedia-t,their u per jbearinz betweemtheirean'walls;andzpistonsslid ends mineexhaust Sleeves; CB1 h vi sfih ablywmounted inihemylinderszand.connected011- D 9 ULPOS -d -b athii e1cy nd rs n do. erativelytorthecranksiiotathewcranh shaft; the exhaust pipes U6 dismissed inla dep n iinternal-combustion engine'iinclud g manner from the intermediate parts44 of the .pair of' complementalsshorizdnt'aily 'zextending cylin m v ni he se of pipes b uc castings disposed in side by side abuttme relaevision f pflq b heeim a el nwmc tionlnd havingiheiinneiv parts;therebshaped h 81 6 j QR G ygh fihe 'fi F lg to'formanbpen'topandfopembcttoxnrciank case pper ends '0! the exhau t pipes dispos d-adj.andi 'comprisinz iateraiiy spacdfside wails and cent to he p r te e ds0 the fuelv supply pairs-0f alimed and abutting fronbg intermediate 1 11t 'sas uafu'e'l n ri 1 M and 'rearwallsg and having-the outenpartstliereof passages I! is subjected to heat 'fiom the *e'iz- 1 mg ra wam-gm e s gg g fi a l mbi s m 6o tiveiy' and"shaped;tc forim-oppositelyexteiiding Tl e herein described engine because of-theateynnderswith"then-31 1911ifendgvdommiinicating rangement and design 'of'thevarious parts there- -with:th k'1 interiori 11; z'poihtsibe'twe n ormay be readily dismantled'andis extremelyeigfiidefront', mt tz -;w n mn.

ncient for its weight.- It occupies ibut a "comthrougii bdlts extendin'g lonitudinaliy parati'vely small 'space and provides-.imaximumethmugh'said pairs izof waflgre pctivelyafida rv vision for the pilot 0tthe airplane in whichthe ing removabiy wsecu're the-twoeastin'gsjtdg'ether, engine ismounted; In addition to-;the foregoing aseparatelyi'oimedsump' fof'iubricanfi disposd the present; engineischaracteriz'ed byithe iact beneath and serving'tocldse the-bpen bottd"that the rocker arms areefliciently andeflectively the crank case andhav'ing fl'an'g at lubricated without venting the rockerboxesfto 7othe'upper part" there6tconn Bl atmospherethecylindei headsareso'dethe-botwm marginal' portionsdf signed that they areinterchahgeableBy iiavot he two eestinesbyv r i in: the-cylindr -and'ci-anizcase-forming parts formed-'cover plate tdr closing th oi't'heengine'in th'e 'ioi'm of'twd' complemental the positioned" abiltneestmge'tn'e"eneme'emboaie 'bu a mail nuu ber '6 n 'm m x.neciingrodstoihecnnksoftheerankshaft.

,3.Aninternaloomhlsflon cngineincluding a pair of cunplemental"horizontally extending castings disposed in side to amendabuttingrelafion and having the inner parts thereof shaped to form anopen top and an open bottom crank oaseand laterally spaced side wallsand pairs of aligned and abutting front and rear walls,- and having theouter parts thereof formed integrally with said inner parts respectivelyand shaped to form oppositely extending cylinders with their innerendsin communication with the crankcase interior, horizontal through-boltsex- 1 tending longitudinally through the front walls and horizontalthrough-bolts extending longitudina'lly through the rear walls forremovably securing the two castings together,. a separately formed sumpfor lubricant disposed beneath and serving to close the open bottom ofthe crank case and removably secured by vertical bolts to the bottomportions of the inner parts of the two castings, a separately formedcover-plate for closing the open top of the crank case positioned inabutment with the upper portions of the inner parts of the castings andsecured removably thereto by vertical bolts, vertically spaced crank andcam shafts extending horizontally through the crank case in parallelrelation with the side walls and iournaled in bearings between the frontw lls and bearings between the rear walls of the two castings, pistonsslidably mounted in the cylinders and connected operatively to thecranks of the crank shaft, gearing for driving the cam shaft from thecrank shaft disposed exteriorly of thejcrank case and positionedadjacent onepair of abutting walls, a casing for the gearing positionedin abutment with the last mentioned pair of walls, and bolts extendingthrough the casing and'said lastmentioned walls and serving with saidcasing to assist the through-bolts, sump.

and cover plate in removably securing the castingstogether.

4. An internal combustion engine including a pair of complementalhorizontally extending castings disposed in side by side and abuttingrelation and having the inner parts thereof shaped to form an open'topand open bottom crank case and comprising laterally spaced side walls,pairs of aligned and abutting front and rear walls and opposedhorizontal webs projecting inwardly from the lower portions of the sidewalls and extending between and joined to the front and rear walls andhaving the outer parts thereof formed integrally with said inner partsrespectively and shaped to form opposed cylinders with the inner endsthereof communicating with the crank case interior at points above saidwebs, horizontal through-bolts extending longitudinally through thefront walls and horizontal through-bolts extending longitudinallythrough the rear walls for removably securing the two castings together,a separately formed sump for lubricant disposed beneath andservingtoclose the open bottom of the crank case and secured removablyto the bottom portions of the inner comprising horizontally extendingshaft actuated tappets slidablyimounted in the webs.

5; Aninternal combustion engine comprisinganopenbottomcrankcasewithlatenllyspaced side walls, opposed'horinontallydisposed cylinders connected to and extending outwardly from the sidewalls and having the inner ends thereof in communication with the crankcase interior, individual cylinder heads connected to the outer ends ofthe cylinders respectively and embodying upper inner end parts formingcombustion chambers for the cylinders, lower outer end parts formingrocker boxes, and intermediate parts extending between the inner andouter end parts and having side by side intake and exhaust pas-.

sages leading to the combustion chambers and extending through theirbottom portions, a crank shaft extending through the crank case, pistonsslidably mounted in the cylinders and operatively connected to thecranksof the crank shaft. a separately formed sump for lubricant disposedbeneath and serving to close the open bottom of the crank case, securedremovably in place, and having in the central portion thereof a anupstanding manifold with the lower end thereof leading through the sumpbottom, a carburetor mounted beneath the sump bottom and having the fueloutlet thereof communicating with the lower end of the manifold, pipesfor supplying gaseous fuel from the carburetor to the combustionchambers disposed beneath, and separate from, the cylinders and havingthe distion engine comprising a crank case with laterally spaced sidewalls and means forming an oil sump, opposed cylinders connected to andextending outwardly from the side walls and having the inner endsthereof in communication with the crank case interior, cylinder headsconnected to the outer ends of the cylinders and shaped to formcombustion chambers for the cylinders, intake and exhaust passages forsaid chambers and rocker boxes, a cam shaft Journaled in the crank case,valves for controlling the intake and exhaust passages, and cam shaftactuated mechanism for operating the valves including horizontal pushrods between the crank case and rocker boxes and pivotally mountedrocker arms in said boxes, of horizontal shroud tubes extending looselyaround the pushrods and extending between and communicating with thecrank caseand the rocker boxes, and means whereby oil is permitted toflow by gravity from the crank case through certain of the shroudtubesinto the rocker boxes and from the 8. The combination with aninternal combusrocker boxes back to the crank case via other shroudtubes.

7, The combination with an internal combustion engine comprising a crankcase with laterally spaced side walls and means forming an oil sump atthe bottom thereof, opposed cylinders connected to and extendingoutwardly from the side walls and having the inner ends thereof incommunication with the crank case interior, cylinder heads connected tothe outer ends of the cylinders and shaped to form combustion chambersfor the cylinders, intake and exhaust passages for said chambers androcker boxes, a cam shaft journaled in the crank case, valves in thecylinder heads for controlling the intake and exhaust passages, and camshaft actuated mechanism for operating the valves including horizontalpush-rods between the crank case and rocket boxes and substantiallyvertically extending centrally pivoted rocker arms in said boxes, ofhorizontal shroud-tubes extending loosely around the push rods andextending between and communicating with the lower portions of the crankcase and therocker boxes, dams in the rocker boxes positioned betweenthe rocker arms and extending from the bottom of the boxes to a pointadjacent to the central portions of the rocker arm, and means wherebyoil is permitted to flow from the crank case through certain of theshroud tubes into the rocker boxes for flow over the dams and from therocker boxes back to the crank case via other shroud tubes.

tion engine comprising a pair or crank case forming castings securedtogether in abutting relation and embodying a pair or laterally spacedside walls and inaddition opposed horizontal webs extending inwardlyirom the lower portions of the side walls and provided with tubularenlargements, opposed cylinders connected to and extending outwardlyfrom the side walls, cylinder heads connected to the outer ends of thecylinders and'shaped to form combustion chambers for the cylinders,intake and exhaust passages for said chambers and rocker boxes, a camshaft joumaled in the crank case, valves in the cylinder heads forcontrolling theintake and exhaust passages, and cam shaft actuatedmechanism for operating the valves including tappets slidably mounted insaid tubular enlargements, horizontal tappet actuated push-rods betweenthe crank case and the rocker boxes, and pivotally mounted rocker armsin said boxes, of horizontal shroud tubes extending loosely around thepush rods and extending between and communicating with the tubularenlargements and the rocker boxes, and means associated with saidtubular enlargements forming upwardly and downwardly facing openingswhereby oil in'the crank case is permitted to flow through certain ofthe shroud tubes into the rocker boxes and from the rocker boxes back tothe crank case via other shroud tubes.

summon r'r. WIEGMAN.

